轴流转桨式水轮机断流反水锤的研究

Study on reverse water hammer occurred to Kaplan turbines during load rejection

针对轴流转桨式水轮机组在甩负荷过渡过程中导叶快速关闭时出现的断流反水锤问题,采用试验与理论分析的方法对发生断流反水锤的界面和临界压力进行了研究。研究结果表明:轴流转桨式水轮机在甩负荷过渡过程中发生断流反水锤的界面是导叶后的断面,而不是尾水管进口断面。总体来说,尾水管进口断面水压在甩负荷过程中是升高的,而导叶后断面的水压随导叶关闭急剧下降。对不同含沙量水的临界空化压力的测定表明,水的临界空化压力远高于常温下清水的汽化压力值0.24m水柱,而且随着含沙量的增大,水的临界空化压力值有所提高。因此,要使用电站实测水质的临界空化压力值来作为判断发生断流反水锤的临界压力。

The phenomenon of water separation and reverse water hammer occurred to Kaplan turbines during rapid closing of guide vane due to load rejection is studied experimentally and analyzed theoretically. The results indicate that the interface of water hammer takes place at the cross section behind the guide vanes. The water pressure at the entrance of draft tube rises in the process of load rejection, but the pressure behind the guide vanes drops rapidly following the closing of operation. Besides, the measurement result of critical cavitation pressure for the water with different concentration of sedimentation shows that this pressure is much higher than the pressure of evaporation （0.24m water column） and increases with the concentration. So that the critical cavitation pressure for judging the happening of reverse water hammer in hydropower station must according to the real evaporation pressure measured from the water in prototype.